He had some properties in Antioch, where he built public baths, some gardens and some villas. He also exchanged letters with Libanius, from whom he received, between 355 and 365, 20 letters still conserved.
After serving under Emperor Constantine I, he became one of the main counsellors of his son Constantius II. As comes, in 345 he wrote a letter to bishop Athanasius inviting him to return to his see in Alexandria, after being deposed by the Arians. In 351 was a member of the tribunal that put under trial bishop Photinus at the synod of Sirmium. In 354 he managed to allow Libanius to return to Antioch. In 358 he held the consulate, and he was yet patricius as of 18 September of that same year. After the death of Constantius and the raise to the power of Julian (361-363), he lost influence.
In 363 he was old; he was in Antioch when Julian died. Datianus followed the new Emperor Jovian to Ancyra, where he passed the winter. When Jovian died, in February 364, Datianus wrote from Galatia to Nicaea, where the imperial court was gathered, to support the election of Valentinian I. That same month (February 364), the population of Antioch burned his house, and the city council was accused of doing nothing to avoid the fire. The people of Antioch sent Datianus a letter asking for his pardon, through the intercession of Libanius; when Datianus gave his pardon, the people was so happy that Libanius, who brought the news, increased his prestige. The following year he was still alive.
- Scott Bradbury, Selected Letters of Libanius: From the Age of Constantius and Julian, Liverpool University Press, 2004, ISBN 0853235090, pp. 80–82.
- Arnold Hugh Martin Jones, John Robert Martindale, John Morris, "Datianus 1", The Prosopography of the Later Roman Empire, Cambridge University Press, 1971, p. 246.